ABSTRACT
Foliar phenol concentrations (total and simple phenols) were determined in Aleppo pine (Pinus halepensis Mill.) needles collected in June 2000, from 6 sites affected by various forms of atmospheric pollutants (NO, NO(2), NO(x), O(3) and SO(2)) monitored during two months. Results show an increase in total phenol content with exposure to sulphur dioxide and a reduction with exposure to nitrogen oxide pollution. p-Coumaric acid, syringic acid and 4-hydroxybenzoic acid concentrations increase with exposure to nitrogen oxide pollution, whereas gallic acid and vanillin decrease in the presence respectively of sulphur dioxide and ozone. This in situ work confirms the major interest of using total and simple phenolic compounds of P. halepensis as biological indicators of air quality.
Subject(s)
Air Pollutants/analysis , Environmental Monitoring/methods , Phenols/analysis , Pinus/chemistry , Plant Leaves/chemistry , Air Pollutants/adverse effects , Biological Assay , Biomarkers/analysisABSTRACT
The leaf essential oils of Cistus monspeliensis plants growing wild on calcareous and siliceous soils in Provence (South of France) were analysed by GC and GC-MS. Qualitative and quantitative differences are noted in the essential oil composition between the Cistus populations from the two soil types. For chemotaxonomic purposes, a characterisation of the two types of oil is proposed.
Subject(s)
Malvaceae/chemistry , Oils, Volatile/chemistry , France , Oils, Volatile/analysis , Plant Leaves/chemistry , SoilABSTRACT
This study focuses on how allelopathic mechanisms may be involved in the floristic composition and dynamics of Cistus albidus shrubbery. Allelopathic potential of essential oils was measured for Lactuca sativa (toxicity for other species) and Cistus albidus (self-toxicity). These oils have little effect on germination but significantly increase, even in low quantities, the number of unviable seedlings and inhibit normal seedling growth. These results explain, at least partially, the existence of monospecific stands over several years and the lack of natural regeneration of the Cistus albidus populations. Bioassays performed using natural aerial leachates of Cistus albidus revealed no significant effects on the above-mentioned parameters. Leaching does not seem to be an important means of allelochemicals release. Nevertheless, essential oils have been quantified in litter and soil, indicating a possible occurrence of allelopathy in such ecosystems.